<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <div id="app">
      <h2>标题</h2>
      <p>我是内容</p>
      <button>提交</button>
    </div>
    <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
    <script>
      new Vue({
        el: '#app',
        created () {
          console.log('created:', this.$el)
        },
        mounted () {
          console.log('mounted:', this.$el)
        }
      })
    </script>
  </body>
</html>